1. Field
This disclosure generally relates to navigation.
2. Background
Positioning determination using satellite navigation systems (SPS) such as the Global Positioning System (GPS) has been widely applied in mobile devices or mobile handsets, such as mobile telephones or smartphones. SPS receivers normally determine their position by computing times of arrival of signals transmitted from a multiplicity of satellites. These satellites transmit, as part of their navigation message, both satellite position data as well as timing data on clock timing, so-called “almanac” and “ephemeris” data. The process of searching for and acquiring satellite signals, reading the data for a multiplicity of satellites and computing the location of the receiver from this data is time consuming, often requiring several minutes. In many cases, this lengthy processing time is unacceptable and, furthermore, greatly limits battery life in miniaturized portable applications.
Conventional SPS receiving equipment works best in open spaces since the satellite signals are weak and their detection and time-of-arrival determination can be degraded by attenuation and/or reflection in other environments (e.g., indoors, or outdoors in the presence of buildings or other objects). Improved SPS receivers provide signal sensitivity that allows tracking satellite signals indoors, or in the presence of weak multipath signals or signals that are pure reflections. The ability to acquire such weak satellite signals, however, remains difficult and typically causes other problems.
Wireless headsets, for example Bluetooth earpieces, and wired headsets have come into greater use as a result of many states adopting hands-free laws. Wireless headsets communicate with a mobile device, typically using Bluetooth communication protocol. Bluetooth earpieces are primarily used to provide audio function.
One area of focus involves hands-free wireless communication where wireless headsets communicate with a local mobile device via a local wireless network.
Because wireless headsets free up a user's hands while the user communicates with friends, family, and colleagues using their mobile device, users are free to perform other tasks, such as driving, shopping, etc. As a result, wireless headsets increase the convenience of using a mobile device.